the Spitzer Extragalactic Representative Volume

Survey:SERVing large telescopes with near-infrared data

Mark Lacy, SERVS team; in particular J-C Mauduit, Jason Surace, Mattia Vaccari, Lucia Marchetti, Greg

Ziemann, Duncan Farrah, Eduardo Gonzales-Solares, Aprajita Verma,

Natalie Christopher, Adam Stanford, Claudia Maraston, Janine Pforr…

Motivation• Current deep surveys not large enough to

include the full range of cosmic environments

• Cosmic variance important even in degree-scale fields.

COSMOS

SERVS XMM-LSS

SERVS ES1

SERVS

EN1

SERVS CDFS

SERVS Lockma

n

Scoville et al. 2008

Depth and area

Choice of fields• SERVS is designed to overlap with surveys of similar scope

in the near-infrared through radio.

• Particularly crucial are the VISTA/VIDEO and UKIDSS/DXS near-IR surveys which match the ~Jy depth of SERVS

• The fields are balanced between north and south, in the centers of five of the six SWIRE fields

Name Area (deg2) Center OverlappingELAIS-S1 3 9.45, -44.0 VIDEO, Hermes L6, ATLAS

XMM-LSS 4.5 35.5, -4.8 VIDEO, Hermes L5

CDFS 4.5 53.08, -28.1 VIDEO, Hermes L2,5, ATLAS

Lockman Hole 4 162.3, +58.11 UDX, Hermes L3,5,S2CLS

ELAIS-N1 2 242.5, +54.5 UDX, Hermes L5, S2CLS

Survey status

• Data taking complete

• Mosaics and preliminary catalogues made.

• Catalogues now being validated

• On track for public release in Spring 2012.

Example: Lockman

Ancillary dataSERVS has a superb set of ancillary data from the optical

through radio:

• Optical: inhomogeneous, but includes CFHTLS (XMM-LSS field), z-band (SpARCs), Subaru SUPRIMECAM, CTIO Mosaic data, SWIRE ancillary data etc…. Also (proposed) VST/VOICE. LSST deep-drilling fields?

• Near-IR: northern fields covered by the UKIDSS DXS survey, southern fields by the VISTA VIDEO survey.

• Mid-IR: SWIRE (3.6-160 microns). (SERVS 3x deeper at [3.6] and [4.5].)

• Far-IR: Herschel/Hermes

• Radio: GMRT data (Garn et al.), VLA surveys (various), ATCA/ATLAS (Middelberg et al.), LOFAR, Meerkat

• Mattia Vaccari will discuss “data fusion” in these fields.

How deep is “deep enough”?

Our AB~25 target gets about 70% of sources in r,i. (Plot courtesy of M. Vaccari.)

Science Goals• SERVS key science goal: “cosmic web” to the

local Universe by placing rare objects/infrequent events in the life of a galaxy (very massive galaxies, QSOs, ULIRGs...) into their cosmological context.

• Characterize the buildup of stellar mass in galaxies from z~6 to present.

• Determine how much star formation is obscured by dust, as a function of epoch.

• Determine the role of environment on galaxy and AGN formation.

• Study the effects of AGN on galaxy formation.

The most massive galaxies

• SERVS will be able to probe the extreme high end of the galaxy mass function at z~2-6 (e.g. Robertson et al. 2007).

• SERVS can thus place excellent constraints on the most massive galaxies, which, in turn, place the strongest constraints on models of galaxy formation.

• Massive hosts of obscured QSOs found already in Spitzer surveys, but need to find quiescent equivalents.

L galaxy (1011 solar masses): solid - [4.5], dot-dashed [3.6], triple dot-dash K-band

Photo-zs and stellar masses

Simulations, led by Maraston & Pforr, are being used to determine which ancillary optical/IR data are most valuable for constraining

redshifts and stellar masses. Expect Δz/(1+z)<<0.1, ΔM/M<0.5 in best cases.

Simulations

• Simulations (P. Thomas and B. Henriques [Sussex]; C. Maraston [Portsmouth]).

• Semi-analytic models on top of the millenium simulations.

• Light cones generated that can be compared directly to observational results.

Obscured star formation• The overlap of SERVS with the Herschel/Hermes GTO

survey allows a study of obscured star formation as a function of stellar mass and environment.

• SERVS is relatively insensitive to dust compared to NIR surveys.

• The Northern/Equatorial SERVS fields also overlap the SCUBA-2 S2CLS survey.

• The Southern/Equatorial fields will be ripe for exploitation by ALMA. Can e.g. use ALMA positions to securely identify Herschel sources with their equivalents in SERVS.

• ALMA can also give unique dynamical information on dusty SERVS galaxies, complementary to ELTs

The role of environment • SERVS will contain ~20 >1014 solar mass dark haloes at z>1.5

• Most of the recent high-z field cluster and protocluster discoveries (out to z~1.7) have either been made with, or made use of IRAC data at ~ SERVS depths.

• Some rich clusters out to z~1.5 are known in the SERVS fields, SERVS will be able to find poorer clusters at these redshifts, study the cluster galaxy luminosity function and identify higher-z cluster candidates.

Geach et al. 2011, submitted

High-z quasars• Our current knowledge of the high-z quasar luminosity

function is poor, particularly at the lower luminosities probed by SERVS.

• SERVS may contain anywhere between 10 to 300 quasars at z>6, and 2 to 50 at z>7 based on current knowledge of the high-z QLF

• Lower end looks more realistic after our initial studies, and a crude estimate of the space density of z~7 objects based on the likely area searched for ULAS1120+0641 (but maybe not given VIKING results...?)

• Our early attempts show Y-band information crucial when searching for z>6.5 objects, as gap between z and J allows interlopers to sneak in.

SERVS and the Giants

• Median SERVS source has i~24, i.e. half of SERVS sources (~106) are essentially impossible to get [high completeness] spectroscopic redshifts for [in ~<3hr] on 8-10m telescopes. Some specific use cases:

• High-z clusters: Spectra needed to confirm cluster membership in high-z cluster candidates found in SERVS. Current limit is about z~2.

• High-z galaxy spectra: Spectroscopic ages, metallicities (Lick Indices) and star formation rates from emission lines.

Science Use Cases-II• AO targets: SERVS can supply many galaxies

near bright stars for routine adaptive optics observations, yielding large samples of very high resolution images of high-z galaxies with good photo-zs.

• Photo-zs: Calibration of SERVS photo-zs below current spectroscopic limits.

• Absorption line science: High signal-to-noise spectra of background UV-bright galaxies can be used for IGM tomography. Cross-correlate absorber properties with intervening SERVS galaxies to study cloud properties as a function of stellar mass, look for evidence of gas inflow/outflow from galaxies etc.

SUMMARY

• SERVS and its multiwavelength companions combine to produce a multi-wavelength dataset between sr-scale surveys (SDSS, DES) and the ~1 deg COSMOS survey.

• SERVS is deep enough to severely challenge current optical/IR telescopes, full spectroscopic follow-up will require the Giants.

• Synergy between optical/IR/submm facilities with the goal of fully understanding massive galaxy formation is within our grasp.

• Warm Spitzer only option for >3 micron surveys by era of Giants (NASA senior review early 2012 for mission extension).

• SERVS data release Spring 2012.

Backup slides

SERVS and ALMA/EVLA

• Southern/equatorial SERVS fields are a high priority for follow-up due to overlap with ALMA. EVLA not so sensitive to CO, but can measure CO(1-0).

• ALMA and EVLA are slow to survey, but can be pointed at specific objects of interest.

• Photo-zs probably good enough for EVLA, and for ALMA if a few settings can be explored.

Example Science: CO and host galaxy masses

Approx log(stellar mass)lo

g(C

O l

um

inosi

ty)

H-band absolute magnitude

SERVS-SWIRE comparison

The role of AGN • SERVS is large enough to contain

significant numbers of luminous, high-z quasars.

• We can thus study the nature and environments of their host galaxies, and of quiescent galaxies of similar masses and luminosities in the same survey.

• Our large multiwavelength dataset will allow us to test models for AGN/quasar feedback with more fidelity than previously possible.

Stellar masses of type-2 quasars

Median of 1<z<3 radio galaxies

SERVS and the Giants

• Giant telescopes are needed to follow up SERVS sources.

• SERVS and its overlapping surveys can act as a finder telescope for interesting targets.

• Already can use in conjunction with ALMA and the EVLA.

Data analysis plan• Images created using an adaptation of the

SWIRE pipeline, led by J. Surace.

• IRAC catalogs produced at UCDavis/LLNL (led by A. Stanford, G. Ziemann).

• Product validation will be performed by separate group (TBD - discussion for this meeting).

• Bandmerging with other surveys led by M. Vaccari.

• We will make the final IRAC catalogs and images publicly available approximately one year after the final data is taken (Spring 2012). Subsequent release of catalogs bandmerged with other surveys will be negotiated as they become public.

AOR design

• Two epochs, separated by days to months for moving object rejection.

• Each epoch has 6x100s frames, using the small cycling dither pattern.

• AORs are 3x3 maps to fill the pre-determined geometry of the fields efficiently.

• Each epoch is time constrained to a few day window to minimize the effects of field rotation during the observations.

• AORs from different epochs have different rotations, improving rejection of artifacts.

• AORs are created using an IDL script and can be generated quickly for any available window given to us by the scheduling team.

Ancillary data gathering• SERVS has been very successful in

obtaining telescope time for follow-up work.

• In particular, we have been awarded several nights at CTIO and Subaru, concentrating on completing the r,i,(z) dataset to AB~25.

• Thanks to Eduardo, Greg, Aprajita, Adam Natalie, JC, Janine and Danielle we are close to completing this phase of the project.

Future ancillary data opportunities

• Optical: Future follow-up: y-band, and also shorter wavelengths (u,g). Also deeper r,i,z, and JHK in North.

• Telescopes/instruments (if we can get them!)

• LBT/LBC

• CFHT/WIRCAM (already have some H-band)

• Blanco/DECam

• VST (Giovanni)

• Subaru HSC...

ALMA

Use 3 settings in band 3 to cover almost 24GHz of bandwidth (25%).

SERVS-2• Proposal submitted, announcement due end

of April.

• Would cover 4 new fields (XFLS [3.8deg2], EN2[3deg2], SA22[4deg2] and VVDS14[3deg2]) and more area [2deg2] in EN1 to push total survey to 33.8deg2, covering >1Gpc3 at z>1.

• Should think about Herschel OT2 and VISTA proposals for SA22 and VVDS14...

• Possible that next Spitzer Cycle will be large proposals only, so may get a second try.